An emerging alternative to classical cryptography in embedded systems is the use of physical unclonable functions (PUFs). PUFs use random manufacturing variations constructively, either to generate cryptographic keys, or to implement physical hash functions for challenge-response authentication. The secret key style of PUF is sometimes called a weak PUF, and PUFs capable of challenge-response hashing are sometimes called strong PUFs. The weak versus strong naming convention is adopted for this disclosure, and further clarify that strong PUF here denotes a circuit that natively provides physical challenge-response hashing, to distinguish it from a weak PUF that is used to key a classical hash function to provide the logical equivalent of a strong PUF.
In this disclosure, a technique is presented for performing a physical unclonable function using an array of SRAM cells (also referring to herein as Bitline PUF). This technique leverages the storage cells and support circuitry of SRAM to save area cost, and achieves high throughput by using individual SRAM columns as parallel PUFs instances.
This section provides background information related to the present disclosure which is not necessarily prior art.